TL;DR Adding Disqus comment system to Jekyll site.

Introduction

Jekyll is great for static site content, but when it comes to dynamic content such as comments, we will have to turn to embed comment system, Disqus for help.

Disqus?

Disqus is an addon that powers discussion threads. For blogs, each discussion thread would represent a blog post, with all the comments under that particular thread.

Go on to Disqus and sign up for an account if you do not already have one. Create your site, add in your site details and all. This site object is where all your threads will be stored.

Login to your dashboard, and navigate to the embedded options there (Admin > Installing Disqus > Universal Code). Disqus provides extensive support for all sorts of platforms. But in our case, we will be using the more generic embed code version.

The code that you have will look something like this:

<div id="disqus_thread"></div>
<script>
var disqus_config = function () {
    this.page.url = PAGE_URL;
    this.page.identifier = PAGE_IDENTIFIER;
};

(function() {var d = document,s = d.createElement('script');s.src = '//ongspxm.disqus.com/embed.js';s.setAttribute('data-timestamp', +new Date());(d.head || d.body).appendChild(s);})();
</script>

How to use?

Think about where you want your comment thread to be placed in. For me, I would want my Disqus comments to only appear in posts. It does not make sense to have a comment thread appearing on the homepage.

With that in mind, we will be placing the Disqus embed code into our _post.html template in _layouts.

How does the code work? To identify which thread you want to load on that particular page, you define the thread’s id as page.identifier in disqus_config(). So what do we use as the page’s unique identifier? Looking at Jekyll documentation, we can see that page.id would be the ideal id for our Disqus thread.

Now make the appropriate changes to the embed code and paste it into wherever you want your comments to be displyed. Now paste the following code into _layouts/post.html:

<div id="disqus_thread"></div>
<script>
var disqus_config = function () {
    this.page.identifier = "{{ page.id }}";
};

(function() {var d = document,s = d.createElement('script');s.src = '//ongspxm.disqus.com/embed.js';s.setAttribute('data-timestamp', +new Date());(d.head || d.body).appendChild(s);})();
</script>

Finishing touches

The final feature that we will add in for this tutorial is the ability to disable comments. To do this we will make use of the front matter YAML that is included in each post.

We will create a new variable nocomment in the post’s front matter(accessible in post.nocomment). If it is not defined, the Disqus thread will be displayed. If the value of page.nocomment is set to true, then the thread will be hidden.

Wrap the disqus thread code with the following Liquid template tags:

{{ "{% unless page.nocomment " }}%}
<div id="disqus_thread"></div>
<script>
var disqus_config = function () {
    this.page.url = {{ "{{ page.url | prepend: site.baseurl | prepend: site.url " }} }};
    this.page.identifier = {{ "{{ page.id " }} }};
};

(function() {var d = document,s = d.createElement('script');s.src = '//ongspxm.disqus.com/embed.js';s.setAttribute('data-timestamp', +new Date());(d.head || d.body).appendChild(s);})();
</script>
{{ "{% endunless " }}%}

The end

Using this technique of including snippets of code into your template, you can greatly extend the functionality of your site. Using this method, you can add in other forms of plugins such as chat and tweet display.